The present invention relates to an ink-jet recording head for ejecting ink droplets through nozzle orifices to record images or characters on a recording sheet, and in particular to the structure of a head cover for protecting a recording head.
As is shown in FIG. 14, an ink-jet recording apparatus 1 is so designed that a carriage 3 is movably attached to a guide member 2 and is connected to a timing belt 6 that is wrapped around a drive pulley 4 and a follow-up pulley 5 and that a pulse motor 7 reciprocally moves the carriage 3 in the direction of the width of a recording sheet 8 (main scanning).
A recording head 9 is located on the face of the carriage 3 opposite the recording sheet 8, or on the bottom face in this example. During the main scanning, ink supplied from an ink cartridge 10 is ejected as ink droplets to the recording sheet 8 to record characters and images thereon.
As is shown in FIG. 15, for the recording head 9, a channel unit 16 is constituted by laminating a nozzle plate, in which a plurality of arrays of a plurality of nozzle orifices 11 are formed, a channel forming substrate 14, in which a plurality of pressure generating chambers corresponding to the nozzle orifices 11 and an ink supply chamber are formed, and an elastic sheet 15, which transmits the vibration of piezoelectric vibrators 12 to change the volume of the pressure generating chambers. The channel unit 16 is bonded on the surface of a casing 17 with an adhesive, and the distal ends of the piezoelectric vibrators 12 are brought into contact with the elastic sheet 15 and are securely retained in the casing 17.
The channel unit 16 is fixed to the casing 17 by a conductive head cover 19 in which a window is formed to expose the nozzle orifices 11, so that the nozzle plate 13 can be prevented from being damaged due to paper stacking, and electric charge can be prevented.
When one part of ink in ink droplets ejected from the nozzle orifices 11 remains on the surface of the nozzle plate 13, this ink may be mixed with ink for the other nozzle arrays, or may change the direction in which ink droplets are dispersed and may deteriorate the printing quality.
In order to wipe ink that remains on the nozzle plate 13, as is shown in FIG. 14, a wiper plate 20 that can ascend and descend on the nozzle face is provided at the location outside the recording available range. When the wiper blade 20 is elevated as needed and is brought in contact with the nozzle plate 13 and when the carriage 3 is reciprocally moved in this condition, the ink remaining on the nozzle plate 13 is wiped away by the wiper blade 20, and the printing quality is recovered.
However, since the external circumference of the recording head 9 is covered with the head cover 19, a wiper blade 20 that is longer than the width of the recording head 9 is elastically deformed by application of a specific force and contacts the nozzle plate 13. If a specific force is not applied, the wiper blade floats in contact with the head cover 19 on the nozzle plate, and does not contact the face of the nozzle plate. Thus, the ink remaining in an area close to the head cover 19 can not be completely wiped.